Defect Sites Research Articles

Role of Myofibroblasts in the Repair of Iatrogenic Preterm Membranes Subjected to Mechanical Stimulation.

We examined the role of myofibroblasts in regulating Cx43 and collagen structure in iatrogenic preterm amniotic membrane (AM) defects subjected to mechanical stimulation. Preterm AM specimens were collected from women undergoing planned preterm caesarean section after in utero intervention for correction of spina bifida by open fetal surgery (n=4 patients; preterm delivery at 34+0weeks to 35+0weeks). Control specimens taken 5cm away from the open fetal surgery defect site were compared with wound edge AM. In separate experiments, the effects of mechanical stimulation and co-treatment with Cx43 antisense on matrix and repair proteins were examined. Specimens were immunostained to detect αSMA and Cx43 in myofibroblasts and counterstained with DAPI to quantify nuclei shape. The direction of collagen fibrils in the wound edge region was examined by SHG imaging. Markers for matrix (collagen, elastin, GAG), inflammation (PGE2) and repair (TGFβ1) were examined by RT-qPCR and biochemical assays. In iatrogenic preterm AM specimens, the diameter of the open fetal surgery defect ranged between 3.5 and 7.5cm. At the wound edge of the open fetal surgery defect, αSMA positive myofibroblasts had deformed nuclei and showed abundant Cx43 localized in the cell bodies or formed plaques. In the fibroblast layer, collagen had degenerated in some regions or had polarity near the wound edge. In preterm AM defects, mechanical stimulation and Cx43 antisense increased the levels of collagen and elastin but not GAG or PGE2 release. Mechanical stimulation increased Cx43 and TGFβ1 gene expression. In open fetal surgery defects, myofibroblasts were elongated with collagen fibrils that either degenerated or had polarity. Whilst cells produced substantially higher Cx43 in the fibroblast than in the epithelial layer, they formed plaques, which may prevent migration and delay healing. Mechanical stimulation of preterm AM enhanced matrix repair proteins and the mechanotransduction should be explored to understand how Cx43 contributes to membrane integrity.

Design of dual-functional Mg/Al layered double hydroxide for smart protective coatings

Although corrosion inhibitors are often added to protective coatings to hinder the corrosion at defect sites, the normal inhibiting pigments are prone to uncontrollable leaching of the active component, leading to fast exhaustion of anti-corrosion properties. Moreover, the protective coatings hide the corrosion, making it difficult to detect the initial degradation processes on the steel. Therefore, it is desirable to develop “self-healing” and “corrosion-sensing” smart solutions for long-term protection and early detection of the onset of corrosion. Herein, we demonstrate the intercalation of corrosion inhibitors and corrosion sensors into layered double hydroxides via an anionic-exchange process and surface modifications with rhodamine B derivative RB2. Electrochemical measurements showed that adding 8 wt% Mg/Al LDH-MoO42−-RB2 pigment in dry paint film provides the epoxy coating with self-healing ability in the event of microcracks for up to 120 h of exposure in salt spray chamber. In addition, pinkish spots were observed near the scribed line at 120 h of salt spray exposure, demonstrating that the added corrosion sensor provided early detection of corrosion upon exposure to Fe3+ ions. The results of this study will aid in reducing the risk of corrosion through self-healing and allow for the detection of corrosion for maintenance purposes, especially in the oil and gas industry.

Insights into novel phosphorus-doped biochar for tetracycline removal: non-radical oxidation and adsorption

Heteroatom doping has been widely recognized as an emerging and promising strategy for material enhancement and the degradation of organic pollutants. However, most heteroatom doping biochars are used to activate, for example, PMS to generate reactive oxygen species (ROS) to degrade organic pollutants instead of investigating their own ability to produce ROS. Herein, phosphorus-doping biochars (PBC) were synthesized at various temperatures for adsorption and degradation of tetracycline (TC). Compared to the pristine biochar (BC-800), PBC-800 exhibited significant enhancements in the specific surface areas (1307.30 m2·g-1), porosity (0.94 cm3·g-1) and higher removal efficiency (1.25 times higher than BC-800). The abundance of functional groups in the PBC-800 such as electron-rich ketone functional groups (C=O), phosphorus-oxygen moieties (P-O), and defective sites within the carbon matrix, have been identified to play crucial roles in TC degradation. The free radical quenching and analysis of electron paramagnetic resonance (EPR) indicated that the presence of persistent free radicals (PFRs) on PBC also influenced the TC removal, and the possible non-radical pathways were proposed. The density functional theory (DFT) calculations proved that PBC-800 exhibited the highest adsorption energy as well as the lowest energy gap between triplet O2 and 1O2, suggesting that the existence of P was conducive to the production of 1O2. This study laid the groundwork for the development of biochars and provided a novel insight into the design of green biomass for effective removal of antibiotics in the future.

Dynamic Passivation of Perovskite Films via Gradual Additive Release for Enhanced Solar Cell Efficiency.

Modifying perovskites with functional additives has proven effective in refining the crystallization process and passivating the defects of perovskite films, thereby ensuring high photovoltaic efficiencies. However, conventional methods that involve pre-mixing additives into the precursor solution often face challenges due to discrepancies in the spatial distribution of slow-diffused additives relative to dynamically formed defect sites, resulting in limited passivation effectiveness. To address this issue, this study innovatively proposes a dynamic passivation strategy that utilizes a pre-passivator to gradually release active additives during the thermal crystallization process of perovskite films. By leveraging the principle of energy minimization, these timely-released additives can interact precisely and selectively with the high-energy defect sites generated during crystallization, thus facilitating efficient additive utilization and in situ real-time defect passivation. Through analysis of crystallization kinetics and carrier dynamic, it is demonstrated that this dynamic passivation approach significantly improves film quality and prolongs carrier lifetime, outperforming traditional pre-mixing tactics. Consequently, the final perovskite solar cell achieves an impressive solar conversion efficiency of 25.33%, along with exceptional stability. This work provides strong support of tailored additive strategies aimed at further enhancing the efficiency of perovskite solar cells and their subsequent commercial applications.

Nitrogen-defective protonated porous C3N4 nanosheets for enhanced photocatalytic hydrogen production under visible light

Defect engineering with morphology control is strategy to tailoring photocatalytic performance of carbon nitride (C3N4) for producing clean hydrogen (H2). Herein, a kind of protonated C3N4 porous nanosheets with nitrogen-defects of N1-vacancy and cyano group (named C3N4-ND) was simple synthesized. In the process, the strong oxidizing nitric acid was used skillfully to introduce N1-vacancy and -CN group into C3N4 and achieves protonation. The nitrogen-defects engineering can shorten band gap, improve the separation of photogenerated carriers. And the defect site, can used as active center and effectively adsorb H+ for efficient photocatalytic hydrogen evolution performance. Simultaneously, the porous nanosheets greatly increase specific area enhanced contact with light and reaction fluids and more reactive sites than bulk C3N4 (BCN). Thus, the C3N4-ND can obtain brilliant photocatalytic hydrogen evolution performance. Typically, C3N4-ND1.7 exhibits excellent photocatalytic H2 evolution rate up to 1.12 mmol·g−1·h−1 for photocatalytic water splitting (PWS) and 39.18 mmol·g−1·h−1 for photocatalytic hydrogen evolution (PHE, 0.5 vol% TEOA as sacrificial agent) under visible light, which has 22.4 and 75.34 times increase over BCN, respectively. This work confirmed the positive effect of defect and morphology engineering on improving the photocatalytic hydrogen evolution performance of C3N4.

Selective hydrogenolysis of furfural-derived tetrahydrofurfuryl alcohol to 1,5-Pentanediol over Ni-Co/La(OH)x bimetallic catalysts

The selective activation of targeted bonds within renewable biomass-derived furanic compounds for the production of high-value alkyl diols holds significant importance for biomass upgrading, necessitating well-defined catalysts and clearly defined catalytically active sites. Herein, 1,5-pentanediol is synthesized through the selective hydrogenolysis of furfural-derived tetrahydrofurfuryl alcohol utilizing Ni-Co/La(OH)x bimetallic catalysts. The La(OH)x with abundant defect sites polarizes Ni-Co alloy for heterocracking of H2, as well as leads to expose more interfacial NiCo-OV-La3+ sites. By harnessing the synergistic interplay between the alloy sites and the interfacial sites, the optimized Ni4Co1/La(OH)x bimetallic catalyst markedly enhances the adsorption of –OH groups in tetrahydrofurfuryl alcohol and facilitates the selective assault of active H species on the C-O-C bonds within tetrahydrofuran rings. This approach markedly elevates the selective hydrogenolysis of tetrahydrofurfuryl alcohol to 1,5-pentanediol, attaining an exceptional selectivity of 88.6 % with a conversion of 98.1 % for tetrahydrofurfuryl alcohol. Furthermore, the Ni4Co1/La(OH)x bimetallic catalyst demonstrates exceptional performance in the one-pot hydrogenation-hydrogenolysis of furfural to 1,5-pentanediol, exhibiting a low activation energy of 17.77 kJ/mol and a high turnover frequency of 192.1 h−1. Notably, the Ni4Co1/La(OH)x bimetallic catalyst showcases remarkable stability. This outcome provides invaluable insights for the advancement of a sustainable process to produce diol monomers from renewable resources with a low carbon footprint.

Scalable fabrication of freely shapable 3D hierarchical Cu-doped hydroxyapatite scaffolds via rapid gelation for enhanced bone repair

Critical-sized bone defects present a formidable challenge in tissue engineering, necessitating innovative approaches that integrate osteogenesis and angiogenesis for effective repair. Inspired by the hierarchical porous structure of natural bone, this study introduces a novel method for the scalable production of ultra-long, copper-doped hydroxyapatite (Cu-HAp) fibers, utilizing the rapid gelation properties of guar gum (GG) under controlled conditions. These fibers serve as foundational units to fabricate three-dimensional porous scaffolds with a biomimetic hierarchical architecture. The scaffolds exhibit a broad pore size distribution (1–500 μm) and abundant nanoporous features, mimicking the native bone extracellular matrix. Physicochemical characterization and in vitro assays demonstrated that the copper doping significantly enhanced osteogenic and angiogenic activities, with optimized concentrations (0.8 % and 1.2 % Cu) facilitating the upregulation of osteogenesis-related genes and proteins, as well as promoting endothelial cell proliferation. In vivo studies further confirmed the scaffolds' efficacy, with the 1.2Cu-HAp group showing a remarkable increase in bone regeneration (bone volume/total volume ratio: 35.7 ± 1.87 %) within the defect site. This research offers a promising strategy for the rapid fabrication of multifunctional scaffolds that not only support bone tissue repair but also actively accelerate the healing process through enhanced vascularization.

Articular cartilage regeneration with a microgel as a support biomaterial. A rabbit knee model

Articular cartilage has limited regenerative capacity, so focal lesions generate mechanical stress in the joint that induces an aggravation of the damage, which ultimately leads to osteoarthritis. We recently suggested the use of microgels at the site of the cartilage defect, as a support material, to generate a biomechanical environment where pluripotent cells differentiate towards the hyaline cartilage phenotype. Here we propose a chondral regeneration strategy based on subchondral bone injury, and filling the defect site with an agglomerate of two types of microspheres, some rigid made of a biodegradable polyester (40 μm mean diameter), and others with a gel consistency made of platelet-rich plasma obtained from circulating blood (70–110 μm diameter). A 3-mm diameter defect was made in the articular cartilage of the knee joint in rabbits, exposing the subchondral bone, in which incisions were made to produce bleeding. Microgels were implanted filling the defect, which was covered with a synthetic membrane of the same polyester. Three months later, cartilage regeneration was analyzed according to the International Cartilage Repair Society (ICRS) guidelines. The newly formed tissue showed histological characteristics of hyaline cartilage, being significantly closer to native cartilage than when only the membrane was implanted, mainly in parameters such as tissue (70.0 ± 20.9) and cell morphologies (100.0 ± 0.0), and surface architecture (90.0 ± 22.4) and assessment (70.0 ± 11.2), with native tissue having a value of 100. Polyester microspheres and membrane were not bioreabsorbed during the three months, but rather moved towards the subchondral bone, leaving space for the organization of the newly formed tissue.

In situ construction of 3D 1T-VS2/V2C heterostructures for enhanced polysulfide trapping and catalytic conversion in lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries represent a promising next-generation energy storage solution, yet their performance is hindered by the insulating nature of sulfur and the detrimental shuttle effect. This study presents the in-situ synthesis of metal-phase 1T-VS2 as a modified separator material on a two-dimensional Mxene substrate V2C (VSC). The synergistic effect of strong adsorption by V2C and highly conductive catalysis provided by 1T-VS2 significantly enhances the transport of ions and electrons between lithium polysulfide and the interface. The combinations of experimental data and density functional theory (DFT) indicate that 1T-VS2, which is characterized by its high density of defective active sites and high conductivity, not only effectively improves the adsorption of lithium polysulfides, but also dramatically lowers the redox energy barrier of Li2S, thereby accelerating the chemical reaction kinetics. As a result, the Li-S cells assembled by the VSC-modified separator exhibit an impressive initial capacity of 1131 mAh/g at 1 C with a capacity decay rate of only 0.05% per cycle. In addition, even after 100 cycles and at a high sulfur loading of 5.6 mg cm−2, the cells maintain a discharge capacity of 817 mAh/g. Impressively, the VSC continues to deliver excellent cycling and rate performance even when the environmental temperature is reduced to 0 °C. These findings offer valuable insights into the potential for the advancement of highly practical Li-S batteries.

Microwave Shock Synthesis of Porous 2D Non‐Layered Transition Metal Carbides for Efficient Hydrogen Evolution

ABSTRACTTransition metal carbides (TMCs) serve as efficient catalysts for electrocatalytic hydrogen evolution reactions (HERs), holding significant importance in promoting hydrogen production for carbon neutrality. To optimize interfacial catalytic activity, structurally designing TMCs into two‐dimensional (2D) and porous structures to expose more practical surface areas and enhance electronic configurations is a common and effective strategy. Particularly, porous 2D non‐layered TMCs (2D NL‐TMCs) demonstrate richer active sites distinct from layered interfacial inertness. However, mainstream selective etching and chemical deposition growth mechanisms struggle to prepare highly active porous 2D NL‐TMCs due to constraints posed by their high structural strength and formation temperature. Herein, we successfully synthesized porous 2D W2C (2D p‐W2C) rapidly using a microwave shock method. Mechanistic verification reveals that leveraging transient high temperature and rapid on‐off properties of microwave effectively combines with an oxidation‐induced porosity mechanism, facilitating the evolution of porous 2D structures. These low‐dimensional nanostructures with abundant edge defect sites aid in efficient adsorption reactions of intermediate species in HER. Moreover, the successful preparation of a series of porous 2D NL‐TMCs (Mo2C, NbC, TaC) confirms the universality of this method, with the synthesized 2D p‐W2C exhibiting optimal HER performance. This strategy offers new insights into the topological synthesis of porous 2D NL crystals.

Enhancing photocatalytic performance in Bi₂WO₆ nanolayers via ultrasound-assisted oxygen vacancy engineering

High-quality two-dimensional Bi₂WO₆ nanolayers were synthesized via hydrothermal processes, with oxygen vacancies introduced through an ultrasound-assisted alkali etching treatment. Comprehensive characterization using Raman spectroscopy, X-ray absorption spectroscopy (XAS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and positron annihilation spectroscopy (PAS) confirmed the presence and effects of these vacancies on the structural and electronic properties of the nanolayers. Raman spectroscopy revealed shifts in vibrational modes, particularly a blue shift in the WO₆ octahedral vibration modes, indicative of oxygen vacancy formation. XPS analysis showed a reduction in the binding energies of the Bi 4f and W 4f orbitals, confirming an altered electronic environment. TEM images demonstrated significant lattice distortions in the oxygen-vacancy-rich regions, particularly disordered WO₆ octahedra and disrupted BiO bond lengths. These distortions are consistent with the structural disorder observed in XAS measurements, which highlighted a reduction in the coordination number of W atoms and a corresponding contraction of WO bond lengths. This charge redistribution between Bi and W atoms due to oxygen vacancies leads to localized structural perturbations, as further evidenced by PAS, which showed increased positron lifetimes associated with vacancy clusters, particularly around the Bi and W atoms. These vacancies create defective sites that trap photogenerated electrons, preventing their recombination with holes, thereby significantly enhancing photocatalytic performance. The enhanced photocatalytic activity was demonstrated by the nearly 98 % degradation of Rhodamine B dye under visible-light irradiation, a substantial improvement over the 70 % degradation achieved by the untreated sample. This work presents an innovative approach for generating stable oxygen vacancies in Bi₂WO₆ nanolayers and offers an in-depth understanding of the mechanisms that enhance photocatalytic performance, providing valuable insights for advancing photocatalysts designed for environmental remediation.

3T-VASP: fast ab-initio electrochemical reactor via multi-scale gradient energy minimization

Ab-initio methods such as density functional theory (DFT) is useful for fundamental atomistic-level study and is widely used across many scientific fields, including for the discovery of electrochemical reaction byproducts. However, many DFT steps may be needed to discover rare electrochemical reaction byproducts, which limits DFT’s scalability. In this work, we demonstrate that it is possible to generate many elementary electrochemical reaction byproducts in-silico using just a small number of ab-initio energy minimization steps if it is done in a multi-scale manner, such as via previously reported tiered tensor transform (3T) method. We first demonstrate the algorithm through a simple example of a complex floppy organic molecule passivator binding onto perovskite solar cell surface defect site. We then demonstrate more complex examples by generating hundreds of electrochemical reaction byproducts in lithium-ion battery liquid electrolyte (many are verified in previous experimental studies), with most trajectories completed within 50–100 DFT steps as opposed to more than 10,000 steps typically utilized in an ab-initio molecular dynamics trajectory. This approach requires no machine learning training data generation and can be directly applied on any new chemistries, making it suitable for ab-initio elementary chemical reaction byproduct investigation when temperature dependence is not required.

Highly Selective Electroreduction of Carbon Dioxide Using Defect-Driven Catalysis.

The production of methanol from the electrochemical reduction of CO2 is a promising method of mitigating climate change while simultaneously producing a useful liquid fuel. In this study, we design self-assembled monolayers (SAMs) of thiols on metal and metal oxide electrodes that operate via cooperative catalysis between the thiolated surface sites and exposed electrode defect sites. This defect-driven mechanism enables the fabrication of SAM-modified ZnO electrodes that yield methanol with an extraordinarily high Faradaic efficiency of up to 92%. To understand the origin of this high selectivity, we study the effect of the chain length of the alkanethiols, different tail functional groups, and applied voltages on catalyst performance. These results combined with density functional theory calculations give a detailed atomic-level understanding of catalyst operation. Furthermore, the SAM linkage tolerates CO2 reduction conditions, and the catalyst's excellent selectivity for methanol remains high after 10 h of continuous conversion. Taken together, these findings with SAM-based electrodes convey a new and facile design strategy for the creation of highly selective CO2 reduction electrocatalysts.

Microenvironment-optimized gastrodin-functionalized scaffolds orchestrate asymmetric division of recruited stem cells in endogenous bone regeneration

The regeneration of osteoporotic bone defects remains challenging as the critical stem cell function is impaired by inflammatory microenvironment. Synthetic materials that intrinsically direct osteo-differentiation versus self-renewal of recruited stem cell represent a promising alternative strategy for endogenous bone formation. Therefore, a microenvironmentally optimized polyurethane (PU) /n-HA scaffold to enable sustained delivery of gastrodin is engineered to study its effect on the osteogenic fate of stem cells. It exhibited interconnected porous networks and an elevated sequential gastrodin release pattern to match immune-osteo cascade concurrent with progressive degradation of materials. In a critical-sized femur defect model of osteoporotic rat, 5% gastrodin-PU/n-HA potently promoted neo-bone regeneration by facilitating M2 macrophage polarization and CD146+ host stem cell recruitment to defective site. The implantation time-dependently increased the bone marrow mesenchymal stem cell (BMSC) population, and further culture of BMSCs showed a robust ability of proliferation, migration, and mitochondrial resurgence. Of note, some of cell pairs produced one stemness daughter cell while the other committed to osteogenic lineage in an asymmetric cell division (ACD) manner, and a much more compelling ACD response was triggered when 5% gastrodin-PU/n-HA implanted. Further investigation revealed that one-sided concentrated presentation of aPKC and β-catenin in dividing cells effectively induced asymmetric distribution, which polarized aPKC biased the response of the daughter cells to Wnt signal. The asymmetric cell division in skeletal stem cells (SSCs) was mechanically comparable to BMSCs and also governed by distinct aPKC and β-catenin biases. Concomitantly, delayed bone loss adjacent to the implant partly alleviated development of osteoporosis. In conclusion, our findings provide insight into the regulation of macrophage polarization combined with osteogenic commitment of recruited stem cells in an ACD manner, advancing scaffold design strategy for endogenous bone regeneration.Graphical abstract

Multifunctional Molecule Passivated Quasi‐2D Perovskite Film for Efficient and Stable Luminescent Solar Concentrator

AbstractQuasi−2D perovskite films with multiple quantum well structures can provide a large Stokes shift and efficient photoluminescence (PL), which have great potential in the application of luminescent solar concentrators (LSCs). However, its low photoelectric conversion efficiency and poor stability remain obstacles to commercial application. Here, a multifunctional molecule additive octyltriphenylphosphonium bromide is introduced to prepare high‐quality perovskite LSCs. The multifunctional molecule can simultaneously passivate perovskite cations and anions, reducing the defect sites and improving the photoluminescence quantum yield (PLQY) of the perovskite nanocrystals. Triphenylphosphine groups with high steric hindrance effect can hinder ion migration; the hydrophobic properties of the long alkyl chain prevent water erosion, which together improves the stability of the perovskite films. The multifunctional molecule passivated perovskite film has a high PLQY of 100% and retains 96% of the initial PL intensity after 30 days of indoor storage. The perovskite LSC device achieves a maximum optical efficiency of 6.5% at a geometric factor of 3.1. The findings open a new way to boost the performance of perovskite‐based LSCs.

Design of Ligand‐Nonbridging Sites in Metal–Organic Frameworks for Boosting Lithium Storage Capacity

AbstractMetal–organic frameworks (MOFs) are lagging in the use of lithium‐ion batteries (LIBs), ascribing to full coordination between metal nodes and organic ligands, to a large extent. By integrating a modulator into a ligand with missing bridging functionality, this study elucidates the role of non‐bridging defect sites in MOFs in tailoring lithium storage performance. A fully bridged pristine MOF (p‐MOF) utilizing the meso‐tetra(4‐carboxylphenyl) porphyrin ligand is compared with a modified MOF containing non‐bridging defects (d‐MOF) introduced by a homologous ligand, tris(4‐carboxyphenyl) porphyrin. Spectroscopic and cryogenic low‐dose electron microscopy techniques verify the presence of non‐bridging defect sites in the d‐MOF and reveal their explicit local structure. Density functional theory calculations show significantly enhanced Li+ adsorption energies and reduced Li+ migration barriers at the non‐bridging sites in the d‐MOF compared to the fully bridging sites in the p‐MOF. As a result, the d‐MOF exhibits exceptional lithium storage performance, achieving a high capacity of 761 mAh g−1 at 0.05 A g−1 and superior rate performance of 203 mAh g−1 at 5 A g−1, which substantially outperform the p‐MOF. This study highlights the potential of modulating MOFs with non‐bridging defects to develop high‐performance LIBs.

Efficient ozone decomposition by optimizing defect sites of NiMn-layered double hydroxides under high humidity air

Ozone is a pollutant that is very harmful to the ecological environment and human health, and layered double hydroxides (LDHs) have attracted much attention in recent years as an excellent anti-aqueous ozone catalyst. A kind of NiMn-LDHs with high defective sites was prepared by a one-step hydrothermal method to catalyze the degradation of ozone. The catalytic activity of NiMn-LDHs against ozone was further enhanced by increasing the concentration of oxygen vacancies on the surface while ensuring the intact structure of LDHs. When Ni/Mn=6:1, the catalyst had the best catalytic performance as well as stability, with 99.3 % degradation efficiency for 50 ppm ozone after 24 h of operation at WHSV=400000 mL·g−1·h−1 and RH=60 %. A series of data show that Ni6Mn-LDHs forms a crystal structure with lower crystallinity, larger specific surface area and smaller grain size. Compared with Ni2Mn-LDHs, the specific surface area of Ni6Mn-LDHs increased from 32.2 m2·g−1 to 171.4 m2·g−1, which is favourable to expose more surface defects. XPS and EPR confirmed that Ni6Mn-LDHs exhibited more surface oxygen vacancies, which plays a key role in the ozone decomposition process. The present study provides important guidance for the developed gaseous ozonolysis catalysts and promotes the practical ozone degradation performance of LDHs.

Trimetallic FeNiCu Atomic Clusters Supported on Carbon Matrix: Highly Active Catalysts for C3H6-SCR of NO.

C3H6-SCR denitrification technology faces catalyst deactivation problems and low catalytic performance at medium-low temperatures. This study utilized the intermetallic synergies to prepare atomic cluster catalysts (FeNiCu/NC) by anchoring Fe-Ni-Cu on a carbon matrix to enhance the C3H6-SCR performance at medium-low temperatures. The synergistic effect of the Fe-Ni-Cu is reflected in the differences in the physicochemical properties of the catalysts, which is proved by several characterization techniques. Results showed that the FeNiCu/NC catalyst had a larger surface area (541.4 m2/g) and there were no metal oxides on the surface of the catalyst but abundant defective sites that anchored Fe/Ni/Cu atoms through N atoms to form M-Nx active sites and atomic clusters. The hollow carbon morphology provides sufficient active sites for C3H6-SCR. The coordination environments of active sites were M-Nx-C, Fe2/FeCu2/FeNi2, Ni3/NiFe/NiCu2, and Cu4/CuFe2/CuNi2, where the synergistic action of trimetal leads to the presence of Fe-Ni-Cu-Nx-C. The synergistic action of the Fe-Ni-Cu significantly improved the C3H6-SCR performance at medium-low temperatures. The FeNiCu/NC exhibited an 81% NO conversion at 150 °C under 2% O2, 15% and 20% higher than FeNi/NC and FeCu/NC catalysts, respectively. Even at 4% O2, the FeNiCu/NC catalyst was active to remove 78% NO and achieve a 93% N2 selectivity at 150 °C and maintained a 100% NO conversion at 300-425 °C. The DRIFTS results demonstrated that NO and C3H6 could combine with active O at metal cluster, M-Nx, or defective oxygen sites to produce various intermediate species, wherein acetates and nitrates were the main active intermediates. Based on the DRIFTS results, a reaction pathway for C3H6-SCR over the FeNiCu/NC catalyst was proposed.

Effect of calcination temperature on CeO2-based catalysts with enhanced photocatalytic degradation of phenol under UV light

This research delves into the photocatalytic degradation of phenol using CeO2 nanoparticles synthesized through solution combustion synthesis (SCS) at varying calcination temperatures (250, 300, 400, 500, and 600 °C). A comprehensive array of characterization techniques was employed, including XRD, FTIR, SEM-EDS, HR-TEM, N2 physisorption, UV–Vis DRS, Raman spectroscopy, and XPS. Our findings reveal a profound influence of calcination temperatures on the presence and quantity of Ce3+ and Ce4+ species, thereby modulating defective sites and surface area, crucial factors impacting performance. CeO2 synthesized at 400 °C stands out with a notable combination of high defects, extensive surface area, and a photocatalytic efficiency of 62 %. This work enhances our understanding of CeO2 photocatalysts for environmental applications and emphasizes the superior performance of mild calcination temperatures in ceria materials.

6-Trifluoromethylnicotinamide Bilaterally Anchored All Cations Implementing Efficient and Humidity-Stable Perovskite Solar Cells.

For organic-inorganic hybrid perovskite solar cells (PSCs), the volatilization of organic components and the presence of undercoordinated Pb2+ ions are the primary causes of device stability imbalance. These factors also serve as significant determinants that restrict the commercialization scale of PSCs. Here, 6-trifluoromethylnicotinamide (TNA) molecules, featuring amide and trifluoromethyl groups at both ends, were introduced as Lewis additives into the precursor solution of perovskite to anchor all cation defect sites and optimize the crystallization process of perovskite. Theoretical calculations confirmed that the -NH2 and C═O groups within the amide group on one side of the TNA molecule synergistically passivated the undercoordinated Pb2+ ions, whereas the trifluoromethyl group on the other side formed hydrogen bonds with the organic components of perovskite. The scorpion-like bilateral all-cation anchoring ability of TNA molecules was further substantiated through experimental characterization. Upon optimization of the TNA treatment concentration, a perovskite film characterized by large grains and a reduced defect density of states was achieved. The photovoltaic performance of PSCs incorporating TNA exhibited significant enhancement with an increase in efficiency from 22.42% (Control) to 24.15%. Under a harsh high-humidity environment, the comprehensive cation passivation effect of TNA significantly hindered the decomposition and phase transition of perovskite films, thereby ensuring excellent humidity stability for the PSCs.